Relationship class processing time in arcgis pro

I've recently been using arcgis pro 2.2.2 to create relationship classes in a file gdb. Performance has been terrible with a one to many relationship taking over 9 minutes to complete (3 records in origin table, 49 in destination table). Switching to arcmap using the same file gdb, feature classes and settings the same relationship takes 44 seconds to complete.

Is the FGDB a disconnected copy of something from SDE? How many relationship classes, and what is the cardinality? Is the symbology the same in Map and Pro? What happens when you do it in Map, save the Map, and import it into Pro? Is the performance hit on making them, or working with them? FGDB compressed, un-compressed? Sensitive data? If not, can you post a zipfile of the final FGDB on here? This will likely be a TS case for sure, though.

I have one table with three records (origin table). I have 8 tables to create relationship classes for (destination tables). Each destination table has 49 records. Cardinality in all cases is one to many.

Is the symbology the same in Map and Pro?

In testing I simply started new projects and brought in the necessary data / tables so default symbology was applied by map or pro.

What happens when you do it in Map, save the Map, and import it into Pro?

I haven't tried this but the realtionship classes I created in map work fine in pro and when I share the map to AGOL through pro.

Is the performance hit on making them, or working with them?

The performance hit is in making them in Pro. Using the geoprocessing tool in the relationship classes toolset the task takes upwards of 9 minutes per relationship class. In ArcMap the same task (using the same data from the same FGDB takes 18-44 seconds.

FGDB compressed, un-compressed?

Uncompressed.

Now I have a question for you Thomas... What is TS?

The data are sensitive but I'll try and obfuscate and send it to you (having tested that problem still exists).